Improvement in molds for casting copper and its alloys



A. S. LAVROFF. Molds for Casting Copper and its Alloys.

AN(),l52,040, Patentedlunel,1874. H9.

@Mp7 fg/MM l' Apcom/ry UNITED STATES PAT ` ALEXANDER STEPHEN LAVROFF, OF ST. PETERSBURG, RUSSIA.

IMPROVEMENT IN NOLDS FOR CASTING COPPER AND ITS ALLOVS.

Specification forming part of Letters Patent No. lfll, dated June 16, 1874; application led September 15, 1873.

To all whom it may concern:

Be it known that I, ALEXANDER STEPHEN LAVROFF, of St. Petersburg, in the Empire of' Russia, have invented an Apparatus for Casting Articles from Copper and its Alloys under Artificial Pressure.

The following' description, taken in connection with the accompanying plate of' drawings hereinafter referred to, forms a full and exact specification, wherein are ,set forth the nature and principles of the invention, by which the same may be distinguished from others ot' a similar class, together with such parts thereof as are claimed as new and are desired to be secured by Letters Patent ofthe United States.

The object of my invention is to cast articles from c'opper and its alloys with artificial pressure in a-more efficacious and better way than has heretofore been employed.

One of the most important deficiencies in articles cast from copper or its alloys in general consists in their defective density, the artcles being penetrated by cavities of greater or less extent, which cavities or porosity ot1 the metal lessens the durability ofthe articles cast, especially if the mass ot' the metal is considerable. In this case the alloy of which the article is cast in cooling sometimes becomes distributed as follows: Either its various constituents separate, oralloys of various fusibility are formed, the most lfusible of them iilling the cavities and pores formed during such cooling. Thus, in the mass of metal, irregular amassments otl this alloy appear, the texture of' the metal becomes iuhomogeneous, and the article indurable. To diminish these important deficiencies the articles are cast nearly al-. ways of a greater height than is required- 27. e., they are cast with a runner; but, in consequence of the expense and many other inconveniences, the height ot' the runner cannot exceed a certain limit, so that notwithstanding it the cast article remains porous, inhomogeneous, and, in. consequence of this, indurable. To fully remove these deficiencies, I found it very useful to apply to the iluid metal in the mold a high artificial pressure immediately after the casting, and to continue this operation until the casting grows hard or even quite cool. Y

I wish it to be understood thatl am aware that the application of pressure to fluid metal in the mold is not new; but the means by which it has hitherto been accomplished, or has been proposed t.) be done, are quite different from the means employed by me, which is as follows:

To produce the pressure, I use the apparatus shown in the accompanying drawing, of' which Figure 1 is a vertical section of' the apparatus on line x a' on Fig. 2, the latter figure being'a plan view.

Tile construction and action of the apparatus are as follows:

On the walls of the foundation A rests a cast-iron beam, B, on which is placedfin the first instance,` a cast-iron plate, C, with a conica-l stopper, l), this stopper forming the bottom of' the mold, 'and the plate C supporting Vthe strong metallic mold, consisting of the pieces E E E. The mold is closed by a solid cast-iron cover, F, which is drawn to the beam B by bolts'G G, connected with butters H H, of vany suitable' construction, which buffers allow the mold, after having been filled with metal, to expand by'heat without damaging' the parts of the apparatus. Into the middle otl the cover F, I cement a cylinder, I, of clay or some other material, which should be a bad conductor of heat, leaving in the axis of' it, which axis is in a line with the axis of the a'pparatus, a runner. On this cylinder I place a cast-iron piston, K, provided likewise with a runner, b, and cu'p L, the whole being supported by thin and iiexible stays a a. The cup L and runner b are also lined with clay. To delay the cooling ofthe top part of the cast article, the upper portion of the widest part of the mold E and the lower surface of' the cover F are also lined with clay, as shown at d d. c c are conical escape-holes for air and gases. The pressure is produced by means ot' aseparate frame, which frame consists of two cast-iron beams, M M, united with each other by bolts N This frame surrounds the mold,

and hangs treely on a crane (not shown in the drawing) by a chain attached to the brace O. To the beam M is attached a plug, P, by means of which, after the mold having been filled with metal and the frame M M lowered, the runner b isclosed and the pressure transmit- -ted to the piston K. To increase this press- Nr OFFICE.

2 l nca-eee ure, l attach to the lower surface ofthe beam 3 a h Ydraulic press, ot' ordinary construction7 the piston of which in descending transmits the pressure to the lower beam, M', of' the frame.

Byprcssing the liquid metal iu the mold according to my method above described, the 'Following conditions, ou which the succesS of the casting' and nature ot' thc metal depend, must be observed: (a.) Any section at a lower level of the mold muy be equal or less, but mut never be greater, than a Section taken at ahigher level. (b) The upper portion of the article cast must be protected from cooling, as much as possible, by providing' corresponding part ot' the mold with a layer of clay or other material, which should be a bad cor.- ductor of heat, (o) The pressing-pistomwhich acts immediately on the metal, should be made of some bad conductor ot' heat, and should press not on the hole surface, but only on the central portion of the column of metal contained in the mold.

I claim as my inventionl. rlhe buffers II 1I,wl1en combined with the sectional inold E as described.

2. The combination of the frame M M N, plug l, piston K, and cla)T cylinder I, as and for the purposes described.

3. The piston K, runner Z), cup L, and cylinder l', when combined together and with the mold, as described.

In testimony that I claim the foregoing' I have hereunto set my hand this 5th dalT of June, 1873. Y

ALEXANDER STEPHEN LAVROFF.

W'ituesses:

NICHOLAS GIIEVALOEF, ALEXANDER B'IICIIELSSOHN. 

